UIAxes' YLim property cannot be listened to

We should attach the listener to the internal Axes object, and not the UIAxes itself. Try this:

hFig = uifigure();
hAx = uiaxes(hFig);
addlistener(struct(hAx).Axes, 'YLim', 'PostSet', @(src, evnt)disp("YLim changed"));
hAx.YLim = [0 2];

In case anybody is wondering, I found this via trial and error.

Tested on R2018a & R2018b.